Contract revenue - Disaggregation of Contract Revenues (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total fee and other revenue	$ 3,176	$ 3,332	$ 3,112	$ 6,508	$ 6,144
Income from consolidated investment management funds, net of noncontrolling interests	950	980	1,017	1,930	1,963
Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,876	2,965	2,853	5,841	5,636
Fee and other revenue - not in scope of ASC 606	339	347	265	686	530
Total fee and other revenue	3,215	3,312	3,118	6,527	6,166
Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,157	1,139	1,109	2,296	2,202
Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	431	470	410	901	808
Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	277	263	291	540	542
Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	145	149	141	294	273
Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,010	2,021	1,951	4,031	3,825
Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	791	863	833	1,654	1,674
Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	24	28	17	52	34
Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	27	31	31	58	62
Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	24	22	21	46	41
Investment Services | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	2,081	2,102	2,013	4,183	3,951
Fee and other revenue - not in scope of ASC 606	258	334	220	592	443
Total fee and other revenue	2,339	2,436	2,233	4,775	4,394
Investment Services | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,147	1,127	1,095	2,274	2,176
Investment Services | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	431	470	411	901	809
Investment Services | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	277	263	291	540	542
Investment Services | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	144	149	140	293	272
Investment Services | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1,999	2,009	1,937	4,008	3,799
Investment Services | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	4	5	4	9	8
Investment Services | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	23	28	16	51	33
Investment Services | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(7)	(12)	(13)	(19)	(27)
Investment Services | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	62	72	69	134	138
Investment and Wealth Management | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	811	878	850	1,689	1,707
Fee and other revenue - not in scope of ASC 606	27	(32)	4	(5)	16
Total fee and other revenue	838	846	854	1,684	1,723
Income from consolidated investment management funds, net of noncontrolling interests	39	(20)	6	19	22
Investment and Wealth Management | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	25	23	20	48	40
Investment and Wealth Management | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Investment and Wealth Management | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Investment and Wealth Management | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	1	0	1
Investment and Wealth Management | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	25	23	21	48	41
Investment and Wealth Management | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	792	862	833	1,654	1,674
Investment and Wealth Management | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1	0	0	1	0
Investment and Wealth Management | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	34	43	44	77	89
Investment and Wealth Management | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(41)	(50)	(48)	(91)	(97)
Other | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(16)	(15)	(10)	(31)	(22)
Fee and other revenue - not in scope of ASC 606	54	45	41	99	71
Total fee and other revenue	38	30	31	68	49
Other | Asset servicing fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(15)	(11)	(6)	(26)	(14)
Other | Clearing services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	(1)	0	(1)
Other | Issuer services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Other | Treasury services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	1	0	0	1	0
Other | Total investment services fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(14)	(11)	(7)	(25)	(15)
Other | Investment management and performance fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	(5)	(4)	(4)	(9)	(8)
Other | Financing-related fees | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	1	0	1
Other | Distribution and servicing | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	0	0	0	0	0
Other | Investment and other income | Operating segments
Disaggregation of Revenue [Line Items]
Total fee revenue - contract revenue	$ 3	$ 0	$ 0	$ 3	$ 0